When applied in marketing settings, the 80–20 Rule usually accurately suggests [approximately] 80% of profits emanate from (about) 20% of customers; 80% of product sales from 20% of products present in a product line (marketing organizations generally sell multiple products); 80% of sales are generated by 20% of advertising, and so forth. The 80–20 Rule is also known as the:

The Pareto principle asserts that 80 percent of output will come from 20 percent of inputs. In different words, 80 percent of the results will come from 20 percent of the action. The Pareto principle is only an observation, not a law. The principle is applicable in business and almost all other disciplines.

In applying the Pareto principle, a business recognizes its best assets as uses efficiently to gain maximum value. The principle observes that similar amounts of input will yield different outputs. For business, results will never be evenly distributed, hence the need to identify and appreciate the minority inputs that will produce the majority of results.